1. Field of the Invention
The present invention relates to a straw for the conservation of small quantities of substances, notably biological substances, in particular biological liquids.
2. Description of the Prior Art
This type of straw, known under the term "French straw", was disclosed for the first time in French patent No. 995 878.
The straws used up to now included a tripartite plug consisting of two pads of a fibrous substance enclosing a powder capable of being transformed in contact with a liquid into an impermeable gel or paste adhering to the wall of the tube, creating a tight stopper.
The tripartite plug straws we have developed and marketed give entire satisfaction. Nevertheless, a certain absorption of liquid contained in the straw may have been found, although very low.
There are straws with different diameters. For straws with a large diameter, for example 3.7 mm, the tripartite plug will be larger and there will be much more absorption. It is therefore desirable not to use a larger plug for a larger diameter straw.
For obvious reasons of economic production, it would generally be advantageous to be able to use plugs of similar sizes for straws with different diameters, regardless of the nature of the plug.
One aim of the invention is to provide a straw including a device enabling the same size plug to be used regardless of the diameter of the straw.
Other aims and advantages of the invention will become apparent upon reading the following description.